[malc]

A big part of a reason why real estate becomes expensive is because of policy & NIMBYs with the perverse incentive to block development so they can increase their property values. Low interest rates, restrictive development policies, retarded tax policies or cultures that give an incentive to leave houses unoccupied go hand in hand with overpriced real estate. You can also add special high property taxes for unused (for corporations) or non-resident (for direct person ownership) for properties to increase property supply.